Keep vanetza-idf in obu-firmware, so a plain clone builds the firmware

obu-firmware builds against the vanetza-idf C-ITS library, which until now
came from the colleague's microbu-esp32c5 tree beside the repository and was
not tracked here, so a clone of this repository could not build the firmware
it ships. The library alone is now part of obu-firmware, as
obu-firmware/external/vanetza-idf: their external/vanetza-idf at commit
cf4b99f, unchanged (9775 files; see its PROVENANCE.md). CMake takes it from
there by default; -DVANETZA_IDF_DIR still points the build elsewhere.

The rest of the colleague's tree (their own VAM firmware, PKI tooling,
station-link Python tools, the V2X2MAP bridge) stays out of this repository
and gitignored; nothing is pushed to their repository. NOTES.md, docs/06,
TODO.md and the pcap verifier's usage line point at the new location.

obu-firmware/external/vanetza-idf/tools/certify/commands/generate-root.cpp

@@ -0,0 +1,124 @@
+#include "generate-root.hpp"
+#include <boost/program_options.hpp>
+#include <chrono>
+#include <iostream>
+#include <stdexcept>
+#include <vanetza/common/clock.hpp>
+#include <vanetza/common/its_aid.hpp>
+#include <vanetza/security/backend_cryptopp.hpp>
+#include <vanetza/security/v2/basic_elements.hpp>
+#include <vanetza/security/v2/certificate.hpp>
+#include <vanetza/security/v2/persistence.hpp>
+#include <vanetza/security/v2/subject_attribute.hpp>
+#include <vanetza/security/v2/subject_info.hpp>
+
+namespace aid = vanetza::aid;
+namespace po = boost::program_options;
+using namespace vanetza::security;
+
+bool GenerateRootCommand::parse(const std::vector<std::string>& opts)
+{
+    po::options_description desc("Available options");
+    desc.add_options()
+        ("help", "Print out available options.")
+        ("output", po::value<std::string>(&output)->required(), "Output file.")
+        ("subject-key", po::value<std::string>(&subject_key_path)->required(), "Private key file.")
+        ("subject-name", po::value<std::string>(&subject_name)->default_value("Hello World Root-CA"), "Subject name.")
+        ("days", po::value<int>(&validity_days)->default_value(365), "Validity in days.")
+        ("aid", po::value<std::vector<unsigned> >(&aids)->multitoken(), "Allowed ITS-AIDs to restrict permissions, defaults to 36 (CA) and 37 (DEN) if empty.")
+    ;
+
+    po::positional_options_description pos;
+    pos.add("output", 1);
+
+    po::variables_map vm;
+    po::store(po::command_line_parser(opts).options(desc).positional(pos).run(), vm);
+
+    if (vm.count("help")) {
+        std::cerr << desc << std::endl;
+
+        return false;
+    }
+
+    try {
+        po::notify(vm);
+    } catch (const std::exception& e) {
+        std::cerr << "Error: " << e.what() << std::endl << std::endl << desc << std::endl;
+
+        return false;
+    }
+
+    return true;
+}
+
+int GenerateRootCommand::execute()
+{
+    auto backend = create_backend_or_throw("default");
+
+    std::cout << "Loading key... ";
+    auto subject_key = v2::load_private_key_from_file(subject_key_path);
+    std::cout << "OK" << std::endl;
+
+    auto time_now = vanetza::Clock::at(boost::posix_time::microsec_clock::universal_time());
+
+    // create certificate
+    v2::Certificate certificate;
+    std::list<v2::IntX> certificate_aids;
+
+    if (aids.size()) {
+        for (unsigned aid : aids) {
+            certificate_aids.push_back(v2::IntX(aid));
+        }
+    } else {
+        certificate_aids.push_back(v2::IntX(aid::CA));
+        certificate_aids.push_back(v2::IntX(aid::DEN));
+    }
+    certificate.subject_attributes.push_back(certificate_aids);
+
+    // section 6.1 in TS 103 097 v1.2.1
+    certificate.signer_info = nullptr; /* self */
+
+    // section 6.3 in TS 103 097 v1.2.1
+    certificate.subject_info.subject_type = v2::SubjectType::Root_CA;
+
+    // section 7.4.2 in TS 103 097 v1.2.1
+    std::vector<unsigned char> subject(subject_name.begin(), subject_name.end());
+    certificate.subject_info.subject_name = subject;
+
+    // section 6.6 in TS 103 097 v1.2.1 - levels currently undefined
+    certificate.subject_attributes.push_back(v2::SubjectAssurance(0x00));
+
+    // section 7.4.1 in TS 103 097 v1.2.1
+    // set subject attributes
+    // set the verification_key
+    Uncompressed coordinates;
+    coordinates.x.assign(subject_key.public_key.x.begin(), subject_key.public_key.x.end());
+    coordinates.y.assign(subject_key.public_key.y.begin(), subject_key.public_key.y.end());
+    EccPoint ecc_point = coordinates;
+    v2::ecdsa_nistp256_with_sha256 ecdsa;
+    ecdsa.public_key = ecc_point;
+    v2::VerificationKey verification_key;
+    verification_key.key = ecdsa;
+    certificate.subject_attributes.push_back(verification_key);
+
+    // section 6.7 in TS 103 097 v1.2.1
+    // set validity restriction
+    v2::StartAndEndValidity start_and_end;
+    start_and_end.start_validity = v2::convert_time32(time_now - std::chrono::hours(1));
+    start_and_end.end_validity = v2::convert_time32(time_now + std::chrono::hours(24 * validity_days));
+    certificate.validity_restriction.push_back(start_and_end);
+
+    std::cout << "Signing certificate... ";
+
+    sort(certificate);
+    vanetza::ByteBuffer data_buffer = convert_for_signing(certificate);
+    certificate.signature = backend->sign_data(subject_key.private_key, data_buffer);
+
+    std::cout << "OK" << std::endl;
+
+    std::cout << "Writing certificate to '" << output << "'... ";
+    save_certificate_to_file(output, certificate);
+    std::cout << "OK" << std::endl;
+
+    return 0;
+}